Custom LED Watch Built Into Antique Pocket Watch Cases — Becomes Cyberpunk Awesome

Sometimes a cool design is built simply of the desire to tinker with unfamiliar technology, and that is definitely the case with these LED watches retrofitted into antique cases. Spark Vulpes, looking to try out watch repair, ended up replacing the internals of a late 1800s/early 1900s pocket watch case, or what was left of it, with digital components. Seeing a nearly empty shell and knowing that crafting an all new mechanical movement was unlikely, they fashioned a five-ring LED timekeeping design and something out of a sci-fi show was born.

The five rings of colored LEDs track seconds, minutes, hours, day of the week, and battery charge — 60 blue LEDs mark seconds, 60 green for minutes, 24 red for hours, and seven orange for days, while the inner ring of three LEDs shows red when charging and green when charged. The final design was born of a few constraints; the original case couldn’t be modified, and the new movement should function similarly to the old one. This means that the time needs to be set with a watch key in the center of the face, and charging must be done through the hole in the back case that would’ve been the winder — the silver case ruled out wireless charging. To make charging work without enlarging the existing hole, the case was fitted with a 2.5mm headphone jack.

Designing a method for setting the time was not as tricky, as the watch face, including the setting hole, is custom-built. However, the interior depth — less than 7mm — limits the choice of rotary encoders to those small enough to accommodate a battery in that depth as well. The watch uses a 380mAh LiPo cell, and the processor is an EFM32 Zero Gecko Cortex-M0-based chip specifically designed for low-power-use applications. This accounts for all the major components, although designing a PCB that accommodates a total of 157 LEDs is a trick in itself.

The watches have a unique look and around 48 hours of battery life with the display. So time is not lost; since there is no place in the compact design for a timekeeping battery, the display does shut off at about 25% battery. If you are interested in the antique/sci-fi aesthetic blend, it’s certainly an interesting project to take a look at. More details can be found in its write-up.